Colorado wildlife officials released 15 wolves from Canada into the central mountains over the last week as part of the second wave of the state's historic, voter-mandated reintroduction of the native predator.

This week, more wolves were released in Colorado as part of an initiative to reintroduce the species to the state. The gray wolf has been endangered in the United States for many years, and recent poaching and habitat loss have further diminished their numbers.

Colorado wildlife officials announced Sunday that they had released a total of 20 gray wolves into the wild over the past eight days, marking the second year of operations for the state’s voter-mandated reintroduction program.